docker publish updates (#1471)

Signed-off-by: Ken Sipe <kensipe@gmail.com>

.goreleaser.yml

@@ -37,12 +37,19 @@ builds:
       - amd64
       - arm
 dockers:
+  # always push a docker image on release for the .Tag version
   - dockerfile: Dockerfile.goreleaser
     binaries:
       - manager
     image_templates:
-      - "kudobuilder/controller:latest"
       - "kudobuilder/controller:{{ .Tag }}"
+  # only update the docker :latest for a full release (not RC)
+  - dockerfile: Dockerfile.goreleaser
+    binaries:
+      - manager
+    image_templates:
+      - "kudobuilder/controller:latest"
+    skip_push: auto
 archives:
   - id: kubectl-kudo-tarball
     builds: